Project Summary The goal of this project is to determine whether metabolism and the gut microbiome underlie hallmark features of the neurodegenerative disease, Familial Dysautonomia (FD). While clinical hallmarks of FD involve the sensory and autonomic nervous system, including cardiovascular instability and orthostatic hypotension with bouts of hypertension, another cardinal feature is impaired gastrointestinal (GI) tract motility. The human GI tract is regulated by over 500 million intrinsic neurons, called the Enteric Nervous system (ENS). The ENS is a component of the Autonomic Nervous System and has been shown to be severely reduced in neuronal number in FD patients. Furthermore, FD patients and mouse models for FD are underweight and mice are essentially devoid of subcutaneous white adipose tissue. The underlying etiology for their reduced mass is not known but recent data has shown that mitochondrial function is impaired in FD patients and mice. The ?gut? and ?brain? communicate extensively and accumulating data demonstrate the strong role the gut microbiome exerts on both metabolism and the nervous system, resulting in exacerbation of neurodegenerative disorders. We hypothesize that FD patients and mice are underweight because they suffer from a global metabolic syndrome induced by a combination of gut microbiome alteration, impaired energy homeostasis and mitochondrial dysfunction, and reduced gut regulation by the enteric, autonomic and sensory nervous systems. Using a multi-disciplinary approach, we will analyze the gut microbiome and metabolome of FD patients and manipulate these systems in mouse models of FD to identify and sort causal mechanisms mediating both metabolic impairments and neuronal health. Although specifically focused on FD, our results will broadly apply to other neurodegenerative diseases, where metabolism and the microbiome are thought to play a role.